// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#include <deque>
#include <set>
#include "leveldb/env.h"
#include "leveldb/slice.h"
#include "port/port.h"
#include "util/logging.h"
#include "util/mutexlock.h"
#include "util/posix_logger.h"

namespace leveldb {

namespace {

static Status IOError(const std::string& context, int err_number) {
    return Status::IOError(context, strerror(err_number));
}

static int check_if_enable(const char *fname) {

    /*if( strstr(fname,".log") || strstr(fname,".ldb")
		|| strstr(fname, "MANIFEST") || strstr(fname, "CURRENT")
		|| strstr(fname, ".dbtmp"))*/
    if(strstr(fname,".log"))
        return 1;
    else
        return 0;
}


class PosixSequentialFile: public SequentialFile {
private:

    std::string filename_;
    FILE* file_;

public:
    PosixSequentialFile(const std::string& fname, FILE* f)
: filename_(fname), file_(f) {

    }

    virtual ~PosixSequentialFile() { fclose(file_); }

    virtual Status Read(size_t n, Slice* result, char* scratch) {
        Status s;
        size_t r;

        r = fread_unlocked(scratch, 1, n, file_);

        *result = Slice(scratch, r);
        if (r < n) {
            if (feof(file_)) {
                // We leave status as ok if we hit the end of the file
            } else {
                // A partial read with an error: return a non-ok status
                s = IOError(filename_, errno);
            }
        }
        return s;

    }

    virtual Status Skip(uint64_t n) {

        if (fseek(file_, n, SEEK_CUR)) {
            return IOError(filename_, errno);
        }
        return Status::OK();
    }
};



// pread() based random-access
class PosixRandomAccessFile: public RandomAccessFile {
private:
    std::string filename_;
    int fd_;

public:
    PosixRandomAccessFile(const std::string& fname, int fd)
: filename_(fname), fd_(fd) { }

    virtual ~PosixRandomAccessFile() { close(fd_); }

    virtual Status Read(uint64_t offset, size_t n, Slice* result,
            char* scratch) const {
        Status s;

        ssize_t r = pread(fd_, scratch, n, static_cast<off_t>(offset));
        *result = Slice(scratch, (r < 0) ? 0 : r);
        if (r < 0) {
            // An error: return a non-ok status
            s = IOError(filename_, errno);
        }
        return s;
    }
};

// Helper class to limit mmap file usage so that we do not end up
// running out virtual memory or running into kernel performance
// problems for very large databases.
class MmapLimiter {
public:
    // Up to 1000 mmaps for 64-bit binaries; none for smaller pointer sizes.
    MmapLimiter() {
        SetAllowed(sizeof(void*) >= 8 ? 1000 : 0);
    }

    // If another mmap slot is available, acquire it and return true.
    // Else return false.
    bool Acquire() {
        if (GetAllowed() <= 0) {
            return false;
        }
        MutexLock l(&mu_);
        intptr_t x = GetAllowed();
        if (x <= 0) {
            return false;
        } else {
            SetAllowed(x - 1);
            return true;
        }
    }

    // Release a slot acquired by a previous call to Acquire() that returned true.
    void Release() {
        MutexLock l(&mu_);
        SetAllowed(GetAllowed() + 1);
    }

private:
    port::Mutex mu_;
    port::AtomicPointer allowed_;

    intptr_t GetAllowed() const {
        return reinterpret_cast<intptr_t>(allowed_.Acquire_Load());
    }

    // REQUIRES: mu_ must be held
    void SetAllowed(intptr_t v) {
        allowed_.Release_Store(reinterpret_cast<void*>(v));
    }

    MmapLimiter(const MmapLimiter&);
    void operator=(const MmapLimiter&);
};

// mmap() based random-access
class PosixMmapReadableFile: public RandomAccessFile {
private:
    std::string filename_;
    void* mmapped_region_;
    size_t length_;
    MmapLimiter* limiter_;

public:
    // base[0,length-1] contains the mmapped contents of the file.
    PosixMmapReadableFile(const std::string& fname, void* base, size_t length,
            MmapLimiter* limiter)
: filename_(fname), mmapped_region_(base), length_(length),
  limiter_(limiter) {

    }

    virtual ~PosixMmapReadableFile() {
        munmap(mmapped_region_, length_);
        limiter_->Release();
    }

    virtual Status Read(uint64_t offset, size_t n, Slice* result,
            char* scratch) const {

        Status s;

        if (offset + n > length_) {
            *result = Slice();
            s = IOError(filename_, EINVAL);
        } else {
            *result = Slice(reinterpret_cast<char*>(mmapped_region_) + offset, n);
        }
        return s;
    }
};

class PosixWritableFile : public WritableFile {
private:
    std::string filename_;
    FILE* file_;

public:
    PosixWritableFile(const std::string& fname, FILE* f)
: filename_(fname), file_(f) {

    }

    ~PosixWritableFile() {
        if (file_ != NULL) {
            // Ignoring any potential errors
            fclose(file_);
        }
    }

    virtual Status Append(const Slice& data) {

        size_t r;

        r = fwrite_unlocked(data.data(), 1, data.size(), file_);
        if (r != data.size()) {
            return IOError(filename_, errno);
        }

        return Status::OK();
    }

    virtual Status Close() {
        Status result;
        if (fclose(file_) != 0) {
            result = IOError(filename_, errno);
        }
        file_ = NULL;
        return result;
    }

    virtual Status Flush() {

#ifdef _DISABLE_SYNC_FOR_DAX
        return Status::OK();
#endif
        if (fflush_unlocked(file_) != 0) {
            return IOError(filename_, errno);
        }
        return Status::OK();
    }

    Status SyncDirIfManifest() {
        const char* f = filename_.c_str();
        const char* sep = strrchr(f, '/');
        Slice basename;
        std::string dir;
        if (sep == NULL) {
            dir = ".";
            basename = f;
        } else {
            dir = std::string(f, sep - f);
            basename = sep + 1;
        }
        Status s;
        if (basename.starts_with("MANIFEST")) {
            int fd = open(dir.c_str(), O_RDONLY);
            if (fd < 0) {
                s = IOError(dir, errno);
            } else {
                if (fsync(fd) < 0) {
                    s = IOError(dir, errno);
                }
                close(fd);
            }
        }
        return s;
    }

    virtual Status Sync() {
#ifdef _DISABLE_SYNC_FOR_DAX
        return Status::OK();
#endif
        // Ensure new files referred to by the manifest are in the filesystem.
        Status s = SyncDirIfManifest();
        if (!s.ok()) {
            return s;
        }
        if (fflush_unlocked(file_) != 0 ||
                fdatasync(fileno(file_)) != 0) {
            s = Status::IOError(filename_, strerror(errno));
        }
        return s;
    }
};

static int LockOrUnlock(int fd, bool lock) {
    errno = 0;
    struct flock f;
    memset(&f, 0, sizeof(f));
    f.l_type = (lock ? F_WRLCK : F_UNLCK);
    f.l_whence = SEEK_SET;
    f.l_start = 0;
    f.l_len = 0;        // Lock/unlock entire file
    return fcntl(fd, F_SETLK, &f);
}

class PosixFileLock : public FileLock {
public:
    int fd_;
    std::string name_;
};

// Set of locked files.  We keep a separate set instead of just
// relying on fcntrl(F_SETLK) since fcntl(F_SETLK) does not provide
// any protection against multiple uses from the same process.
class PosixLockTable {
private:
    port::Mutex mu_;
    std::set<std::string> locked_files_;
public:
    bool Insert(const std::string& fname) {
        MutexLock l(&mu_);
        return locked_files_.insert(fname).second;
    }
    void Remove(const std::string& fname) {
        MutexLock l(&mu_);
        locked_files_.erase(fname);
    }
};

class PosixEnv : public Env {
public:
    PosixEnv();
    virtual ~PosixEnv() {
        char msg[] = "Destroying Env::Default()\n";
        fwrite(msg, 1, sizeof(msg), stderr);
        abort();
    }

    virtual Status NewSequentialFile(const std::string& fname,
            SequentialFile** result) {

        FILE* f = fopen(fname.c_str(), "r");
        if (f == NULL) {
            *result = NULL;
            return IOError(fname, errno);
        } else {
            *result = new PosixSequentialFile(fname, f);
            return Status::OK();
        }
    }

    virtual Status NewRandomAccessFile(const std::string& fname,
            RandomAccessFile** result) {
        *result = NULL;
        Status s;

        int fd = open(fname.c_str(), O_RDONLY);
        if (fd < 0) {
            s = IOError(fname, errno);
        } else if (mmap_limit_.Acquire()) {
            uint64_t size;
            s = GetFileSize(fname, &size);
            if (s.ok()) {
                void* base = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
                if (base != MAP_FAILED) {
                    madvise(base, size, MADV_SEQUENTIAL);
                    *result = new PosixMmapReadableFile(fname, base, size, &mmap_limit_);
                } else {
                    s = IOError(fname, errno);
                }
            }
            close(fd);
            if (!s.ok()) {
                mmap_limit_.Release();
            }
        } else {
            *result = new PosixRandomAccessFile(fname, fd);
        }
        return s;
    }

    virtual Status NewWritableFile(const std::string& fname,
            WritableFile** result) {
        Status s;

        FILE* f = fopen(fname.c_str(), "w");
        if (f == NULL) {
            *result = NULL;
            s = IOError(fname, errno);
        } else {
            *result = new PosixWritableFile(fname, f);
        }
        return s;
    }

    virtual Status NewAppendableFile(const std::string& fname,
            WritableFile** result) {
        Status s;
        FILE* f = fopen(fname.c_str(), "a");
        if (f == NULL) {
            *result = NULL;
            s = IOError(fname, errno);
        } else {
            *result = new PosixWritableFile(fname, f);
        }
        return s;
    }

    virtual bool FileExists(const std::string& fname) {
        return access(fname.c_str(), F_OK) == 0;
    }

    virtual Status GetChildren(const std::string& dir,
            std::vector<std::string>* result) {
        result->clear();


        DIR* d = opendir(dir.c_str());
        if (d == NULL) {
            return IOError(dir, errno);
        }
        struct dirent* entry;
        while ((entry = readdir(d)) != NULL) {
            result->push_back(entry->d_name);
        }
        closedir(d);
        return Status::OK();
    }

    virtual Status DeleteFile(const std::string& fname) {
        Status result;
        if (unlink(fname.c_str()) != 0) {
            result = IOError(fname, errno);
        }
        return result;
    }

    virtual Status CreateDir(const std::string& name) {
        Status result;
        if (mkdir(name.c_str(), 0755) != 0) {
            result = IOError(name, errno);
        }
        return result;
    }

    virtual Status DeleteDir(const std::string& name) {
        Status result;
        if (rmdir(name.c_str()) != 0) {
            result = IOError(name, errno);
        }
        return result;
    }

    virtual Status GetFileSize(const std::string& fname, uint64_t* size) {
        Status s;
        struct stat sbuf;
        if (stat(fname.c_str(), &sbuf) != 0) {
            *size = 0;
            s = IOError(fname, errno);
        } else {
            *size = sbuf.st_size;
        }
        return s;
    }

    virtual Status RenameFile(const std::string& src, const std::string& target) {
        Status result;

        if (rename(src.c_str(), target.c_str()) != 0) {
            result = IOError(src, errno);
        }
        return result;
    }

    virtual Status LockFile(const std::string& fname, FileLock** lock) {
        *lock = NULL;
        Status result;
        int fd = open(fname.c_str(), O_RDWR | O_CREAT, 0644);
        if (fd < 0) {
            result = IOError(fname, errno);
        } else if (!locks_.Insert(fname)) {
            close(fd);
            result = Status::IOError("lock " + fname, "already held by process");
        } else if (LockOrUnlock(fd, true) == -1) {
            result = IOError("lock " + fname, errno);
            close(fd);
            locks_.Remove(fname);
        } else {
            PosixFileLock* my_lock = new PosixFileLock;
            my_lock->fd_ = fd;
            my_lock->name_ = fname;
            *lock = my_lock;
        }
        return result;
    }

    virtual Status UnlockFile(FileLock* lock) {
        PosixFileLock* my_lock = reinterpret_cast<PosixFileLock*>(lock);
        Status result;
        if (LockOrUnlock(my_lock->fd_, false) == -1) {
            result = IOError("unlock", errno);
        }
        locks_.Remove(my_lock->name_);
        close(my_lock->fd_);
        delete my_lock;
        return result;
    }

    virtual void Schedule(void (*function)(void*), void* arg);

    virtual void StartThread(void (*function)(void* arg), void* arg);

    virtual Status GetTestDirectory(std::string* result) {
        const char* env = getenv("TEST_TMPDIR");
        if (env && env[0] != '\0') {
            *result = env;
        } else {
            char buf[100];
            snprintf(buf, sizeof(buf), "/mnt/pmemdir/leveldbtest-%d", int(geteuid()));
            *result = buf;
        }
        // Directory may already exist
        CreateDir(*result);
        return Status::OK();
    }

    static uint64_t gettid() {
        pthread_t tid = pthread_self();
        uint64_t thread_id = 0;
        memcpy(&thread_id, &tid, std::min(sizeof(thread_id), sizeof(tid)));
        return thread_id;
    }

    virtual Status NewLogger(const std::string& fname, Logger** result) {
        FILE* f = fopen(fname.c_str(), "w");
        if (f == NULL) {
            *result = NULL;
            return IOError(fname, errno);
        } else {
            *result = new PosixLogger(f, &PosixEnv::gettid);
            return Status::OK();
        }
    }

    virtual uint64_t NowMicros() {
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return static_cast<uint64_t>(tv.tv_sec) * 1000000 + tv.tv_usec;
    }

    virtual void SleepForMicroseconds(int micros) {
        usleep(micros);
    }

private:
    void PthreadCall(const char* label, int result) {
        if (result != 0) {
            fprintf(stderr, "pthread %s: %s\n", label, strerror(result));
            abort();
        }
    }

    // BGThread() is the body of the background thread
    void BGThread();
    static void* BGThreadWrapper(void* arg) {
        reinterpret_cast<PosixEnv*>(arg)->BGThread();
        return NULL;
    }

    pthread_mutex_t mu_;
    pthread_cond_t bgsignal_;
    pthread_t bgthread_;
    bool started_bgthread_;

    // Entry per Schedule() call
    struct BGItem { void* arg; void (*function)(void*); };
    typedef std::deque<BGItem> BGQueue;
    BGQueue queue_;

    PosixLockTable locks_;
    MmapLimiter mmap_limit_;
};

PosixEnv::PosixEnv() : started_bgthread_(false) {
    PthreadCall("mutex_init", pthread_mutex_init(&mu_, NULL));
    PthreadCall("cvar_init", pthread_cond_init(&bgsignal_, NULL));
}

void PosixEnv::Schedule(void (*function)(void*), void* arg) {
    PthreadCall("lock", pthread_mutex_lock(&mu_));

    // Start background thread if necessary
    if (!started_bgthread_) {
        started_bgthread_ = true;
        PthreadCall(
                "create thread",
                pthread_create(&bgthread_, NULL,  &PosixEnv::BGThreadWrapper, this));
    }

    // If the queue is currently empty, the background thread may currently be
    // waiting.
    if (queue_.empty()) {
        PthreadCall("signal", pthread_cond_signal(&bgsignal_));
    }

    // Add to priority queue
    queue_.push_back(BGItem());
    queue_.back().function = function;
    queue_.back().arg = arg;

    PthreadCall("unlock", pthread_mutex_unlock(&mu_));
}

void PosixEnv::BGThread() {
    while (true) {
        // Wait until there is an item that is ready to run
        PthreadCall("lock", pthread_mutex_lock(&mu_));
        while (queue_.empty()) {
            PthreadCall("wait", pthread_cond_wait(&bgsignal_, &mu_));
        }

        void (*function)(void*) = queue_.front().function;
        void* arg = queue_.front().arg;
        queue_.pop_front();

        PthreadCall("unlock", pthread_mutex_unlock(&mu_));
        (*function)(arg);
    }
}


namespace {
struct StartThreadState {
    void (*user_function)(void*);
    void* arg;
};
}

static int setaffcntr=0;

static int setaffinity()
{
    int s, j;
    cpu_set_t cpuset;
    pthread_t thread;
    int numproc = sysconf(_SC_NPROCESSORS_ONLN);

    if(setaffcntr)
        return 0;

    setaffcntr++;
    thread = pthread_self();
    CPU_ZERO(&cpuset);
    //CPU_SET(1, &cpuset);
    for (j = 0; j < 8; j++)
        CPU_SET(j, &cpuset);

    fprintf(stdout,"setaffinity_np %u\n",numproc-1);
    s = pthread_setaffinity_np(thread, sizeof(cpu_set_t), &cpuset);
    if (s != 0)
        return 0;

}

static void* StartThreadWrapper(void* arg) {
    StartThreadState* state = reinterpret_cast<StartThreadState*>(arg);
    state->user_function(state->arg);
    delete state;
    return NULL;
}

void PosixEnv::StartThread(void (*function)(void* arg), void* arg) {
    pthread_t t;
    StartThreadState* state = new StartThreadState;
    state->user_function = function;
    state->arg = arg;
    PthreadCall("start thread",
            pthread_create(&t, NULL,  &StartThreadWrapper, state));
}

}  // namespace

static pthread_once_t once = PTHREAD_ONCE_INIT;
static Env* default_env;
static void InitDefaultEnv() { default_env = new PosixEnv; }

Env* Env::Default() {
    pthread_once(&once, InitDefaultEnv);
    return default_env;
}

}  // namespace leveldb
